ADHD is a developmental disorder with high prevalence among Puerto Rican children. Research evidence suggests that higher order cognitive processes known as executive function are impaired in this disorder. Recently, Barkley has advanced the theory that the fundamental deficit in ADHD is the inability to inhibit or delay prepotent or dominant responses to an event, which in turn disrupts executive functions that are crucial in the development of self-regulation of behavior. Elaborating on Barkley's theory and supporting research, Tannock and Schachar have proposed that the core systems of ADHD and the difficulties in language use exhibited by children with the disorder are related to deficits in the executive functions. These authors recognize that executive functions and language go through developmental changes. Their work allows us to set forward predictions regarding deficits in specific executive functions and language abilities in ADHD, as well as developmental delays in both domains. We propose a cross sectional design that combines quantitative and qualitative methods of analysis to study executive functions and language abilities in ADHD (n=90) and normal (n=90) children of three different age-groups (6-7, 8-9, 10-11 years). Specifically, our study is aimed to: (1) determine the extent to which the combined Type of ADHD differs from a normal control group in the following domains of executive and non- executive functions: response inhibition; internalization of speech (verbal working memory); non-verbal fluency), and language abilities; 2) to evaluate the hypothesis of whether ADHD constitutes a developmental delay by examining the manner in which the deficits in response inhibition, executive functions, and expressive language in ADHD change as a function of development from years 6 to 11, in comparison to normal children; and (3) to examine the specificity of the relationship between expressive language and executive functions.